Hydrogenation of alkenyl amines



United States Patent 3,116,331 HYDRQGENATHUN 0i? ALKENYL AMENES Douglas G. Norton, Berkeley, and John L. Van Winide, Castro Valley, Califi, assignors to Shell Oil Company, New York, N.Y., a corporation of Deiaware No Drawing. Filed May 19, 1961, Ser. No. 111,169 '6 Claims. (260-533) This invention relates to the preparation of alkyl amines. More particularly, it relates to a process for the preparation of dialkyl secondary amines from tri(beta,gammaalkenyl) amines.

Diallyl amine is an important chemical of commerce and is readily prepared by the reaction of an allyl halide, such as allyl chloride, with ammonia. In this process, however, undesirably large amounts of triallyl amine are formed for which no ready market may exist. It is therefore frequently required to convert the triallyl amine to some more economically attractive product and to do so with a minimum of caiptal expenditure and other costs.

It is an object of the present invention to provide a method for the conversion of triallylic amines to the corresponding dialkyl secondary amines. Another object of the invention is the provision of a catalytic process for conducting this conversion in an economic and eliective manner. Another object of the invention is the provision of a process for hydrogenating triallylic amines in the presence of hydrogenation catalysts, while still another object is the provision of a continuous process for such hydrogenation. Other objects will be apparent from the following detailed discussion of the invention.

These objects are accomplished in the invention by the process which comprises hydrogenating tri(beta,gamma-alkenyl)amine in the presence of a hydrogenation catalyst, and separating the resulting dialkyl amine from the tri beta, gamma-alkenyl) amine.

By tri(beta,gamma-alkenyl)amine is meant an amine consisting of a nitrogen atom whose three valences are each directly connected to an allylic substituent. Such compounds have in general the structure wherein each R is selected from the group consisting of the hydrogen atom and lower alkyl. Preferred compounds are those wherein each of the allylic substituents has from 3 to carbon atoms.

Exemplary of such compounds are tri(2-butenyl)-amine; tri(2-pentenyl)amine; tri(2-decenyl)amine; tri(5-methyl- Z-hexenyl) amine; tri(4,S-dimethyl-Z-heptenyl)amine; tri(menthallyl) amine and tri(ethallyl)amine. Particulaly preferred because of the excellent yields afforded by its use is triallyl amine.

The process is readily conducted by reacting together a tri(beta,gamma-alkenyl)amine of the type described with hydrogen in contact with a hydrogenation catalyst. The reaction may be conducted in either the liquid or the vapor phase. The most satisfactory catalysts to use, because of the ease with which they may be separated from the reaction system, are the solid hydrogenation catalysts. Such catalysts are preferably selected from metals of groups I, II and IV through VIII of the periodic table, their alloys and derivatives such as their sulfides, oxides and chromites. Examples include silver, copper, iron, manganese, molybdenum, platinum, chromium, cobalt, rhodium, tungsten, mixtures of metals, such as coppersilver mixtures, copper-chromium mixtures, nickel-cobalt mixtures, and their derivatives such as copper oxides, copper chromite, nickel sulfide, silver sulfide, and the like. Particularly preferred catalysts are the members of the group consisting of nickel, copper, cobalt, iron, chromium,

3,116,331 Patented Dec. 31, 1963 ice silver, palladium and platinum, and their oxides, sulfides and chromites. Exemplary or" such catalysts are Raney nickel and copper chromite. These catalysts may be employed in a finely divided form and dispersed in and throughout the reaction mixture, or they may be employed in a more massive state, either in essentially the pure state or supported upon or carried by an inert carrier such as pumice, kieselguhr, diatomaceous earth, clay, alumina, charcoal, carbon or the like, and the amine and hydrogen contacted therewith, as by flowing the mixture over or through a bed of the catalyst or according to other methods known in the art.

The amount of catalyst employed may vary over a Wide range, depending on the nature of the amine, the type of catalyst employed, the reaction conditions, and the like. In general, the amount of catalyst employed will vary from about 0.1% w., based on the amine, to about 40% w. on the same basis, but larger or smaller amounts, i.e., up to about an equal weight, based on the amine, are effective. Most preferred range is from about 1% w. to about 15% w. of catalyst, based on the amine, although from 23% w. may be adequate.

The reaction may be conducted in any suitable apparatus. It is an important feature of the invention that the hydrogenation takes place very readily under comparatively mild hydrogenation conditions, and so the use of extremely high-pressure equipment is not required, thus contributing materially to the economy with which the process may be practiced. Thus, while superatmospheric pressures as high as 3000 p.s.i.g. or 5000 p.s.i.g. may be employed for the hydrogenation, it proceeds suitably in general at hydrogen pressures of from about atmospheric to about 1000 p.s.i.g. Best operation is achieved at hydrogen pressures of only about 50 to about p.s.i.g.

Relatively low temperatures may also be employed. Thus, while the hydrogenation of the allylic amine may be conducted at temperatures up to the decomposition temperature of the amine, it will proceed readily at temperatures of from about 0 C. to about 300 C. The preferred range for optimal results is from about 50 C. to about 100 0, illustrating the unexpectedly mild conditions under which the hydrogenation of the invention occurs.

Hydrogenation of the tri(beta,gamma-alkenyl)amine under the conditions recited is readily accomplished under any circumstances permitting intimate contact between the amine, the hydrogen and the catalyst. Thus, either the liquid phase or the vapor phase may be employed. When conducting the reaction in the liquid phase, inert solvents may be used as diluents or for temperature control. Typical solvents include paraffins such as cyclohexane, pentane, hexane, heptane and octane; ethers such as ethyl ether, isopropyl ether, butyl ether, tetrahydrofuran and dioxane; alcohols such as methanol, ethanol, propanol, butanol, cyclohexanol and the like; and esters such as ethyl acetate, amyl acetate, butyl propionate and similar liquids. Preferred solvents are those having up to 6 carbon atoms.

The reaction is readily followed by observation of the uptake of hydrogen. At the close of the reaction, the desired dialkyl secondary amine may readily be separated from the reaction mixture by conventional methods, such as fractional distillation, solvent extraction, crystallization, selective sorption and the like. Unreacted tri(beta,gamma-alkenyl)amine and any saturated trialkyl amine may conveniently be recycled after separation of the desired dialkyl amine, or all saturated amines may be recovered and separated, and the allylic amines recycled.

It will be seen from this description of the invention that a wide variety of dialkyl amines may be easily prepared from tri(beta,gamma-alkenyl)amines wherein each of two alkenyl substitutents have the same number of carbon atoms as the alkyl substituents of the product. In accordance with the notation above, these amines will have the structure (CR CR CR NH, where R as alkly may have up to 4 carbon atoms. Thus, tri(2-butetil nyl)amine is easily converted to dibutyl amine; tri(2-pen- 5 saturated amines therein had the following composition: tenyl)amine to dipentyl amine; tri(methallyl)amine to diisobutyl amine; and triallyl amine to dipropyl amine. Percent Comer. The novel and unexpected features of the invention are Amine -r 0. SiOn, illustrated by the following examples. It should be undercent W stood, however, that the examples are merely illustrative 7 and are not to be regarded as limitations to the appended itiii 5%:0 xiii claims, since the basic teachings thereof may be varied at Heavy ends will, as will be understood by one skilled in the art. In the examples, the proportions are expressed in parts by We claim as our invention: i h unless th i t d, 1. The process comprising reacting tri(beta,gamma- Examples aIkenyDamme, the alkenyl being from 3 to 10 carbon atoms, with hydrogen in the presence of a hydrogenation A series of hydrogenations was conducted in a 300 cc. catalyst at atmospheric to 5000 p.s.i.g. ressure and from rocking autoclave disposed so that hydrogen under about 0 C. to about 300 C. temperature to form the constant pressure could be charged thereto. Triallylamine corresponding dialkyl secondary amine. feed (98.91% w.trially1 amine, 1.09% diallylamine) was 2. The process comprising reacting tri(beta,gammaemployed. Product analysis was made by gas-liquid alkenyl)amine, the alkenyl being from 3 to 10 carbon chromatography. The results obtained are presented in atoms, with hydrogen in the presence of Raney nickel at the following table. atmospheric to 5000 p.s.i.g. pressure and from about 0 Percent Products, Mole percent Wt. Hydro- H2 Moles Moles Triallyl Raney genation Pressure, Hydrogen 'lime, Amine Charged Nickel Temp., C. p.s.i.g. Absorbed Minutes n-Propyl Di-n- Trim- Catalyst Amine propyl propyl Amine Amine 1.25 1. 75 23-117 200 4. 57 1300 2. 5s 42. 75 50.8 1.25 2. 92 70-181 200-600 4. 72 225 4. 0 50. 7 41. 3 0.262 as a 49.39%

solution in oetane 9. 73 178 215 300 0. 817 27 O. 97 41. 8 42. 6 584 2. 44 149-154 80-160 2. 022 1. 25 4s. 6 50. 2

Using the technique described, a sample of triallyl amine C. to about 300 C. temperature to form the correspondwas hydrogenated over 2.4% w. Raney nickel at about ing dialkyl secondary amine. 150 C. and 80-160 p.s.i.g. until an amount or" hydrogen 3. The process comprising reacting triallyl amine with equivalent to 94% of onedouble bond had occurred. The hydrogen in the presence of a hydrogenation catalyst at product distribution in the treated amine was as follows: atmospheric to 5009 P- Pressure and from about C. to about 300 C. temperature to form di-n-propyl Amine Mole percent amine.

n-Propylamine 0.64 4- The process of claim 3 wherein the catalyst is Raney 'Di-n-propylamine 16.3 ni k l- Diallyl-n-propylamine 20.9 The process of claim 3 wherein the catalyst is copper 'Allyl di-n-propylamine 6.8 chromite.

Triallylamine 54.5 6- The process comprising reacting tri(beta,garnmaalkenyl)amine, the alkenyl being from -3 to 10 carbon In another experimenta flask was charged with a mixatoms, with hydrogen in liquid phase in the presence of a ture of triallyl 'amine containing about 2.5% W. Raney hydrogenation Catalyst at atmosphelicto 5000 P- 'g-PI nickel and hydrogen was bubbled through the stirred mix- Sure and from about Q about temperature ture. A slight back pressure of about 2 inches of mercury to form the Corresponding dlalkyl Secondary amine- 1 was maintained by using a mercury bubbler at the outlet. Refemnces Cited in the file of this p e The temperature rose autogeneously to about 50 C. and remained at that point throughout the reaction. The hydrogenation was conducted'in this manner for 12 hours,

FOREIGN PATENTS 313,934 Great Britain Jan. 14, 1928 

1. THE PROCESS COMPRISING REACTING TRI(BETA,GAMMAALKENYL) AMINE, THE ALKENYL BEING FROM 3 TO 10 CARBON ATOMS, WITH HYDROGEN IN THE PRESENCE OF A HYDROGENATION CATALYST AT ATOMPSHERIC TO 5000 P.S.I.G. PRESSURE AND FROM ABOUT 0*C. TO ABOUT 300*C. TEMPERATURE TO FORM THE CORRESPONDING DIALKYL SECONDARY AMINE. 